482 PATHOGENIC BACTERIA. 



" In such cases the bacillus can be found upon the in- 

 flamed serous membranes, in the inflammatory exudates, 

 in the spleen in large numbers, in the adrenals, the liver, 

 the kidneys, and sometimes in the lungs. The blood is 

 also infected, but to a rather less degree. 



' ' In cases described as chronic, the bacillus disappears 

 completely in from five to twenty-four hours, and pro- 

 duces but one lesion, a small abscess at the point of inoc- 

 ulation. 



" Sanarelli has observed that if some of the poisonous 

 products of the colon bacillus or the Proteus vulgaris be 

 injected into the abdominal cavity of an animal recover- 

 ing from a chronic case, it speedily succumbs to typical 

 typhoid fever." 



Petruschky * found that mice that recovered from sub- 

 cutaneous injections of typhoid cultures frequently suf- 

 fered from a more or less widespread necrosis of the skin 

 at the point of injection. 



I experienced great difficulty in immunizing a horse to 

 the disease, because every injection of virulent living 

 organisms was followed by a necrosis equalling in size the 

 distended area of subcutaneous tissue. 



Large quantities of filtered cultures produce symptoms 

 similar to those resulting from inoculation with the bacilli. 



Animals can easily be immunized to this bacillus, and 

 then, according to Chantemesse and Widal, develop in 

 their blood an antitoxic substance capable of protecting 

 other animals. Stern 2 has also found that in the blood 

 of human convalescents a substance exists which has a 

 protective effect upon guinea-pigs. His observation is in 

 accordance with a previous one by Chantemesse and 

 Widal, and has recently been abundantly confirmed. 



The immunization of dogs and goats by the introduc- 

 tion of increasing doses of virulent cultures has been 

 achieved by Pfeiffer and Kolle 3 and by Loftier and Abel. 4 



1 Zeitschrift fur Hygiene, 1892, Bd. xn., p. 261. 



» Ibid., 1894, xvi., p. 458. 3 Ibid., 1896. 



* Centralbl.f. Bakt. u. Parasitenk., Jan. 23, 1896, Bd. xix., No. 23, p. 51. 



